1. Field of the Invention
The present invention relates to a press machine equipped with a flywheel. More specifically, the present invention relates to a press machine including a press center aligned with guide members which minimizes rotational force on the press and increases pressing precision and force during operation.
2. Description of the Related Art
Referring now to FIGS. 4(A) and 4(B), a conventional press 101 includes a frame 102 having a ‘C-type’ frame or structure. It should be understood that conventional presses, known as one-point presses, typically include this ‘C-frame’ type of structure. C-frame structures have stress and accuracy disadvantages that adversely affect quality and cost, later described.
A pair of individual guides 103 are at a left and right side of frame 102. During operation, a slide 104 operates between guides 103. Guides 103 act to guide and support slide 104 and allow slide 104 to raise up and down in operation while maintaining approximate alignment, as will be explained.
A bolster 108 is on frame 102 at a position facing slide 104. A die 107 is positioned between slide 104 and bolster 108.
A flywheel 111 is in conventional press 101. Flywheel 111 is equipped internally with a clutch/brake mechanism (not shown) that aid operation. A motor 105 rotates flywheel 111. A drive shaft 112 is rotatably disposed on frame 102. Flywheel 111 is on one end of drive shaft 112. A set of gears 112a are on drive shaft 112.
A crank shaft 113 is rotatably attached at the top of frame 102. Crank shaft 113 includes an eccentric section 113a. A connecting rod 106 connects to eccentric section 113a of shaft 113.
Crank shaft 113 connects to slide 104 through connecting rod 106. A main gear 114 is fixed to an end of crank shaft 113. Main gear 114 operably meshes with and engages gears 112a. 
A drive mechanism 110 includes crank shaft 113, main gear 114, drive shaft 112, and flywheel 111.
Now referring additionally now to FIG. 5, guide 103 is positioned behind a press center P and symmetrically to the left and right of press center P. Press center P is positioned away from guide 103.
During operation, press center P is the center of pressing operation and pressing force on slide 104.
It should be understood, that since press center P and guide 103 are not aligned along the direction of force, the position results in undesirable rotational force placed upon guide 103 during pressing operation.
During operation, slide 104 presses against die 107 and exerts force through press center P. Since press center P and guides 103 are not aligned, slide 104 transmits the force vector into a rotational force upon guides 103.
A pair of slide-side gibs 104a are at the left and right side of slide 104. A front liner 103a, a side liner 103b, and a rear liner 103c support slide-side gib 104a during operation.
During operation, a drive force of motor 105 causes flywheel 111 to rotate. Drive shaft 112 rotates when the clutch in the clutch/break mechanism (not shown), mounted in flywheel 111, connects. Drive shaft 112 rotates main gear 114. Main gear 114 rotates crank shaft 113. Connecting rod 106 on eccentric portion 113a causes slide 104 to operate.
In conventional press 101, the sliding sections of drive mechanism 110 and guide 103 are lubricated with grease.
It is to be understood that during operation of conventional press 101, with the C-shaped frame 102, an undesirable problem called “frame gap opening” or simply ‘gapping’ occurs. Frame gap opening occurs when an opening of frame 102 is opened as a result of a pressing operation and slide 104 receiving pressing forces.
Additionally, a set of corners R1, R2, and R3 on frame 102 experience particularly high stress during pressing operation of conventional press 101. Additionally, damage to frame 102 may result at corners R1, R2, or R3, during severe pressing operation, and cause failure of frame 102 or failure to operate press 101. This type of frame damage is very expensive and time consuming to remedy.
A third problem may result during operation of conventional press 101. Frame gap opening may additionally cause slide 104 to tilt relative to conventional press 101. Where slide 104 tilts, this adversely affects levelness in relation to bolster 108, die 107, and may cause slide 104 to fail.
Fourth, die 107 may tilt due to the adverse effects of the “gaping” problem. Where die 107 tilts, the life span of a die and die equipment may be reduced. Further, when die 107 tilts, the precision of conventional press 101 is reduced thus increasing quality rejects and increasing costs.
It is to be further understood, that “frame gap opening” or “gaping” can cause “breakthroughs” in stamping operations, ruining the stamped item, reducing quality, increasing costs, increasing noise, and increasing vibration.
Various solutions have been proposed to prevent the “gaping,” tilting, and breakthrough problems associated caused by the construction of conventional presses 101. These conventional solutions have focused on increasing the thickness of the side plates of frame 102 and placing a separate structurally supportive bridge across the conventional press 101 opening.
These representative solutions adversely increase the size, weight, and cost of conventional press 101 and are thus undesirable. The negative results to the conventional fixes for the above problems adversely affect users of conventional press 101 and make simple and quick operation difficult.
It is to be understood that in conventional press 101, the use of separate parts in frame 102 in and of itself, increases the above described ‘gapping’, tilting and associated problems. These separate parts have varying thicknesses to compensate for the stress placed on each part during operation. Further, the mechanical connectors, i.e., bolts, between the multiple frame parts are subject to failure, and the connectors act as stress concentrators, the use of mechanical connectors further increases the above described problems.
It is to be understood that in conventional press 101, grease is used as a lubricant on the various sliding sections and drive mechanism. The use of grease makes it difficult to maintain precision operations, provide low clearance at sliding sections for levelness, and maintain operational cleanliness thus reducing quality.